Über den Autor Ralf Spenneberg: Ralf Spenneberg has used Linux since 1992 and worked as a system administrator since 1994. During this time he worked on numerous Windows, Linux and UNIX systems. The last 6 years he has been working as a freelancer in the Linux/UNIX field. Most of the time he provides Linux/UNIX training. His specialty is network administration and security (firewalling, VPNs, intrusion detection). He has developed several training classes used by Red Hat and and other IT training companies in Germany. He has spoken on several SANS conferences and even more UNIX/Linux specific conferences. He was chosen to be member of the program comitee of the Linux Kongress and the GUUG Frühjahrsfachgespräch. 2002 he published his first german book "Intrusion Detection für Linux Server". His second german book "VPN mit Linux" was published in 2003. The last book in this series "Intrusion Detection und Prevention mit Snort & Co." was published in November 2004. At the moment he writes a book on Linux Firewalling to be published in Febuary 2006.